Image Tools

Image Dimension Checker

Check any image's dimensions instantly — width and height in pixels, aspect ratio, megapixels, file size and format. Just pick an image; nothing is uploaded.

Click to choose an image

Need more than one step? Batch-process, convert and ZIP your images in Image Studio — all in your browser.

How to check an image's dimensions

Choose any image your browser can display — JPG, PNG, WebP, GIF and more.
Read the width and height in pixels, the simplified aspect ratio and the megapixel count.
Check the file size and format shown alongside.
Compare the numbers with what your upload form, printer or website needs, and resize if they don't match.

Common image dimensions and their aspect ratios

The aspect ratio shown is the exact ratio reduced to whole numbers, so some familiar sizes look unusual: 1200 × 630, widely described as 1.91:1, reduces to 40:21. Both describe the same shape.

Dimensions	Aspect ratio	Megapixels	Where you'll see it
1920 × 1080	16:9	2.1	Full HD screens, video frames, slides
3840 × 2160	16:9	8.3	4K UHD video and screens
4032 × 3024	4:3	12.2	Standard 12 MP phone photo
6000 × 4000	3:2	24.0	24 MP DSLR and mirrorless cameras
1080 × 1350	4:5	1.5	Instagram portrait post
1200 × 630	40:21	0.76	Link preview images (usually called 1.91:1)
1280 × 720	16:9	0.92	YouTube thumbnail
1500 × 500	3:1	0.75	X (Twitter) header

Why the dimensions can look swapped

Phone cameras usually store every photo in the sensor's landscape orientation and add a small tag telling viewers to rotate portrait shots by 90°. Browsers apply that tag, so this checker reports the image the way you see it — a portrait photo shows as 3024 × 4032. Some older programs read the raw stored size and report 4032 × 3024 for the same file. Neither is wrong: one describes the stored pixels, the other the displayed picture.

Checking dimensions without a tool

The checker is quicker when you're comparing several files, or when you want the aspect ratio and megapixels worked out for you.

Windows: right-click the file → Properties → Details, and look under Image.
Mac: select the file and press Cmd + I, then expand More Info — or open it in Preview and choose Tools → Show Inspector.
iPhone: open the photo in Photos and swipe up, or tap the info button, to see its resolution and megapixels.
Android: in Google Photos, open the image and swipe up to see details including the resolution.

Dimensions that upload forms and platforms check

When a website rejects an image for its size, it's usually checking one of three things: a minimum, so the picture isn't blurry when displayed; a maximum, so it doesn't overwhelm storage or screens; or an exact shape. Knowing the width, height and ratio before you upload tells you which fix you need — enlarging rarely helps, cropping fixes the shape, and resizing down fixes the maximum.

Megapixels are the quickest way to compare photos of different shapes. A 3000 × 4000 portrait and a 4000 × 3000 landscape are both 12 megapixels, while a 1920 × 1080 screenshot is only about 2 — six times less detail, whatever its file size suggests.

Frequently asked questions

How do I check an image's dimensions?

Choose an image and the tool shows its width and height in pixels, plus aspect ratio, megapixels, file size and format.

What are megapixels?

Megapixels are the total pixels (width × height) in millions — a 4000×3000 image is 12 MP.

Is my image uploaded?

No. The image is read locally in your browser and never uploaded.

Is it free?

Yes, free with no sign-up.

Does a bigger file always mean a bigger image?

No. File size depends on format and compression as well as pixel count. A heavily compressed 4000 × 3000 JPG can be smaller than a 1000 × 1000 PNG screenshot, which is why this checker shows dimensions and file size side by side.

What's the difference between dimensions and resolution?

Dimensions are the pixel width and height. Resolution is often used loosely for the same thing, but strictly it means pixel density — pixels per inch — which only matters when printing. The Image DPI Checker shows that.

How many megapixels do I need for a print?

For a sharp 6 × 4 inch print at 300 DPI you need 1800 × 1200 pixels, about 2.2 megapixels. An A4 print at 300 DPI needs 2480 × 3508 pixels, about 8.7 megapixels.